1. Field of the Invention
The present invention relates to the field of orthogonal frequency division multiplexing (OFDM) technology. More particularly, the present invention relates to a coarse frequency synchronization method and apparatus in an OFDM receiver.
2. Description of the Related Art
OFDM technology relates to digital modulation for satisfactorily minimizing interference by multiple-path or fading channels near each other in frequency. In particular, since OFDM technology has excellent spectrum efficiency, much research is conducted regarding its application to various fields of wireless communications. However, OFDM technology is vulnerable to frequency synchronization and symbol timing synchronization. OFDM technology has been adopted as a standard by a European digital video broadcasting (DVB) method, the IEEE 802.11a standard that is a wide-band wireless local area network (LAN) that supports transmission of a signal at a speed of 20 Mbps or more, and a physical layer of a high performance LAN (HIPERLAN/2) suggested by broadband radio access network (BRAN) European Telecommunications Standard Institute (ETSI). In particular, a coarse frequency synchronization method is applicable to the European DVB.
In a conventional frequency synchronization method, a correlation value is obtained by determining the length of a summation interval according to a phase coherence bandwidth, dividing it into sub-bands, computing correlation values for the respective sub-bands, and averaging the correlation values, so as to supplement a correlation bandwidth reduced by a frame synchronization offset. In this way, it is possible to solve problems caused by the frame synchronization offset, thus enabling coarse frequency synchronization. However, this method is substantially difficult to be realized, since a sample offset must be compensated for within a range of ±15 samples.